Field of the Invention
The present invention relates to a magnetic head. More particularly, it relates to a structure for supporting a magnetic recording medium (hereinbelow, referred to as a recording medium) to be used for the magnetic head in, for instance, a floppy disk drive unit.
When there is a minute gap or spacing between a magnetic head and a recording medium in, for instance, a floppy disk drive unit, the output of a signal written in or reproduced from the recording medium is attenuated.
In case of reproduction of the signal, the output loss L is expressed as follows: ##EQU1## where d is an amount of the spacing and .lambda. is the wavelength of a signal recorded in the recording medium. Namely, the wavelength of 1 .mu.m causes loss of about 6 dB even though the spacing is only 0.1 .mu.m.
A vertically magnetizing and recording system enables the wavelength of a recorded signal to be shorter than that of a conventional horizontally magnetizing and recording system. Accordingly, more careful consideration should be made on the spacing in the floppy disk drive unit employing a vertically magnetizing and recording medium. Various measures have been taken to minimize the loss.
FIG. 11 is a diagram showing the conventional vertically magnetizing and recording head, in cross-section, disclosed in Japanese Unexamined Patent Publication No. 82220/1982. In FIG. 11, a reference numeral 1 designates a main magnetic pole comprising a high magnetically permeable thin film 1a and a non-magnetic holder 1b. A numeral 2 designates an auxiliary magnetic pole opposing the main magnetic pole 1. The main and auxiliary magnetic poles 1, 2 constitute a magnetic pole assembly for recording magnetic signals in a magnetic recording medium and for reproducing the signals recorded in the medium. A numeral 3 designates a coil wound on the outer periphery of the auxiliary magnetic pole 2 to effect recording and reproducing of the magnetic signals; a numeral 4 designates a resilient body such as felt mounted on the top surface of the auxiliary magnetic pole 2; a numeral 5 designates a magnetic recording medium to be placed between the main magnetic pole 1 and the auxiliary magnetic pole 2, and a numeral 6 designates a spring means such as a coiled compression spring which applies a load to the auxiliary magnetic pole 2 whereby the recording medium 5 is held by the main magnetic pole 1 and the resilient body 4. Accordingly, a gap or a spacing formed between the main magnetic pole 1 and the recording medium 5 is minimized by the spring action of the spring means 6.
However, in the conventional magnetic head, when the recording medium 5 is moved in the direction indicated by an arrow mark as shown in FIG. 12, a force caused by a friction produced between the recording medium 5 and the resilient body 4 acts on a contacting area whereby the resilient body 4 is deformed, which results in ununiform contacting pressure of the recording medium 5 to the main magnetic pole 1.
A phenomenon of stick slip is produced due to a frictional force between the recording medium 5 and the resilient body 4 having specified characteristics, and a pressure of contact varies with the lapse of time. When the felt is used as the resilient body 4, it is difficult to control the thickness of it. Especially, when a contacting force of the spring means 6 is poor, it is extremely difficult to maintain a uniform pressure of contact between the recording medium 5 and the main magnetic pole 1. In the conventional magnetic head, it is necessary to increase a pressure of contact by means of the spring means 6 in order to stably maintain the spacing between the main magnetic pole 1 and the recording medium to be 0.1 .mu.m or lower. In this case, however, wearing and damage of the main magnetic pole 1 and the recording medium 5 are disadvantageously caused even though a stable pressure of contact can be obtained. Further, if fine particles are deposit on the surface of the resilient body 4, the recording medium 5 is damaged so that restoration of the recording medium is impossible.
Thus, the conventional magnetic head had the problem that an ununiform pressure of contact is easily caused between the main magnetic pole 1 and the recording medium 5 due to deformation of the resilient body 4 and uneven thickness of the resilient body. While a strong contacting force is needed to minimize the spacing and to maintain the spacing under stable condition, a strong contacting force inevitably results wearing of the magnetic head and damage of the recording medium to thereby invite dropping out of signals and breakage of recorded data whereby reliability of the magnetic head is impaired.
FIG. 13 is a diagram showing another conventional magnetic head as disclosed in Japanese Unexamined Utility Model Publication No. 749/1985. The magnetic head is so constructed that the recording medium 5 is urged to a magnetic pole 16 by an air ejected from a nozzle 15 which is connected to an air compressor 13 through a pipe 14. However, a region where a pressure given by the air is applied is extremely small, and the force is approximately equal to a concentrated load. Accordingly, although the recording medium can be brought to contact with the magnetic pole, deformation of the recording medium at an early stage and a slanting movement (movement of seesaw) of the recording medium during its revolution can not be suppressed. Further, in the conventional magnetic head, since a highly pressurized air is ejected in the atmosphere, excessive disturbance of an air stream takes place at the end of the ejected air stream (which is called fluttering phenomenon), whereby the slanting movement of the recording medium is further remarkable.